By using Cerno’s calibration techniques, users of High Mass Accuracy (HMA) instruments can now improve the results of formula identification and obtain higher quality, reproducible data through accurate line-shape calibration.

Using MassWorks sCLIPS, the latest addition to the MassWorks mass spectrometry software suite, the collaborative research was able to further improve formula ID by the use of Spectral Accuracy and thus help achieve unique formula determination. MassWorks was originally launched in 2006, and is a post acquisition software system using Cerno’s MS Integrity calibration technology to work directly with data from a wide range of mass spectrometers.

Formula ID normally requires accurate mass measurements typically provided by high resolution Time-of-Flight (TOF), Orbitrap or FT-ICR instrumentation. With its resolving power reaching 1,000,000:1, an FT-ICR instrument is capable of sub-ppm mass accuracy, a level considered sufficient by most high end users.

However, where true unknown formula ID is required in applications such as natural product or metabolomics research, even such impressive levels of mass accuracy could lead to many possible formulas, especially at masses of 400Da or above.

‘How to go beyond mass accuracy and determine the correct formula amongst the many possible candidates becomes a problem crying out for a solution’, said Dr. Tolstikov, director of Metabolomic Core Facility at UC Davis.

Cerno’s sCLIPS technology, when applied to FT-ICR MS data, corrects the instrument line-shape and enables exact isotope modelling when comparing the MS response of an unknown ion against theoretically calculated responses for all possible candidate formulas. This allows spectral differences as small as 0.1 per cent to be measured which enables highly confident formula ID. One of the benefits of the approach is that it requires no known calibration ions, and instead uses the fully resolved monoisotopic peak of the unknown ion itself for the sCLIPS line-shape calibration.